In general, cooling of a high power light source, e.g., comprising a light emitting diode (LED), assembled at a small area, i.e. with a high power density, is desired but difficult to achieve. A small available area further necessitates an efficient utilization of available space between other functional parts of the lighting device, e.g., housing, optics, driver boards etc. Also, there is required a user friendly thermal management regarding noise and warm air flow.
To achieve these conflicting goals, known lighting devices, like LED lamps, operate at a lower power, may divide the brightness and hence the power dissipation by arranging LEDs on a comparatively large area, and mostly use passive heat sinks. Passive heat sinks are typically arranged laterally around or below a light source and provide relatively widely spaced cooling fins creating air flow channels reaching from bottom to the very top to allow natural convection; the warm air exit is typically around the fins with a warm air tail opposite to the direction of gravity. Some lighting devices, however, employ an active cooling forcing an air flow onto a heat sink in thermal connection with the hot light sources, often via a submount substrate. The heat sink is regularly a separately manufactured element fixed by a support structure, e.g., the housing. The known heat sinks employed for active cooling are attached below the heat sources facing the fan. Particularly with compact designs, the assembly and adjustment of the various parts becomes complex and costly.